1. Field of the Invention
The present general inventive concept relates to an inkjet image forming apparatus, and, more particularly, to an inkjet image forming apparatus having an ink sensing device to sense ejection of ink.
2. Description of the Related Art
An image forming apparatus is an apparatus to form an image on a printing medium according to input image signals. Examples of the image forming apparatus include printers, copiers, facsimiles, devices combining functions thereof, and the like.
Image forming apparatuses may be classified, according to a printing method thereof, into electro-photographic image forming apparatuses and inkjet image forming apparatuses. Of these, inkjet image forming apparatuses print an image by ejecting fine droplets of ink to a printing medium at desired positions.
A conventional inkjet image forming apparatus includes an inkjet head provided with a plurality of nozzles. A high quality image can be printed on a printing medium when droplets of ink are normally ejected from the nozzles of the inkjet head. However, occasionally, some of the nozzles may exhibit ejection failure, causing deterioration of print quality.
Stabilizing the print quality of the inkjet image forming apparatus requires a mechanism to restore a defective nozzle or compensate for print failure due to the defective nozzle. To realize the mechanism, a process to specify a position of the defective nozzle must be performed.
To specify the position of the defective nozzle, the inkjet image forming apparatus may be provided with an ink sensing device. The ink sensing device ascertains whether or not the nozzles of the inkjet head normally eject ink, thereby detecting a presence of a defective nozzle.
The ink sensing device has a likelihood of being contaminated by ink scattered from the inkjet head during a printing operation or maintenance operation, or dust scattered from a printing medium being transferred. The contaminated ink sensing device may exhibit deteriorated operational ability, or may completely cease to function.